Hi. I am working on an enemy class in my tile-based 2d rpg game in xna, and I am having difficulty with the AI. I attempted to make my own custom method; It works sometimes but not always. Right now, I am testing it on a simple map with a river running through it and a bridge. When my player's X position is the same as the bridge's, the enemy is able to reach me. When it is not, the enemy simply walks towards the river until it can't move anymore (enemy's can't enter water). By the way, the enemy and the player are on opposite sides of the river. Before trying this method, I looked into the A* method. Unfortunately, I am only in 8th grade, so it is a bit too confusing for me. Could you please try to modify or explain to me why my code is not working. I do understand why it is not working, but do not understand how to fix the problem.

Here is the AI Method.:


public void Move()
{
if (movetimer > 0)
{
movetimer--;
}

if (movetimer == 0)
{
int TargetX;
int TargetY;

List<Vector2> possibleTiles = new List<Vector2>();
List<Vector2> movableTiles = new List<Vector2>();
List<Vector2> movableDesiredTiles = new List<Vector2>();
if (X < Main.map.grid.GetLength(1))
{
possibleTiles.Add(new Vector2(X + 1, Y));
}
possibleTiles.Add(new Vector2(X, Y + 1));
if (X > 0)
{
possibleTiles.Add(new Vector2(X - 1, Y));
}
possibleTiles.Add(new Vector2(X, Y - 1));

foreach (Vector2 tile in possibleTiles)
{
if (tile.X < Main.map.grid.GetLength(1) && tile.Y < Main.map.grid.GetLength(0))
{
if (Main.map.grid[(int)tile.Y, (int)tile.X] != 2)
{
movableTiles.Add(new Vector2(tile.X, tile.Y));
}
}
}

foreach (Vector2 tile in movableTiles)
{
if (Vector2.Distance(new Vector2(tile.X, tile.Y), new Vector2(Main.player.X, Main.player.Y)) < Vector2.Distance(new Vector2(X, Y), new Vector2(Main.player.X, Main.player.Y)))
{
movableDesiredTiles.Add(new Vector2(tile.X, tile.Y));
}
}
if (movableDesiredTiles.Count > 0)
{
Vector2 mostDesiredTile = new Vector2(X, Y);
int distanceX;
int distanceY;
int totalDistance = 100;
foreach (Vector2 tile in movableDesiredTiles)
{
int specificDistance;
distanceX = Main.player.X - X;
if (distanceX < 0)
{
distanceX *= -1;
}
distanceY = Main.player.Y - Y;
if (distanceY < 0)
{
distanceY *= -1;
}
specificDistance = distanceX + distanceY;
if (specificDistance < totalDistance)
{
mostDesiredTile = new Vector2(tile.X, tile.Y);
totalDistance = specificDistance;
}
}
TargetX = (int)mostDesiredTile.X;
TargetY = (int)mostDesiredTile.Y;
X = TargetX;
Y = TargetY;


}

movetimer = 60;
}


Didn't look through all your code but if you need a simple A* tutorial then i reccomend this one.
http://www.policyalmanac.org/games/aStarTutorial.htm
Being in the 8th grade shouldn't stop you from learning it. Its fairly simple if you can visualize it. All you need to do is reread the parts that give you trouble and you should have no problem.